Results from the Telescope Array Experiment

Transcription

1 Results from the Telescope Array Experiment Hiroyuki Sagawa (ICRR, University of Tokyo) for the Telescope Array AlbaNova University Center on /08/1 H. 7th TeVPA in Stockholm 1

2 Outline I. Introduction II. TA results (for UHECR above ev) Spectrum (FD mono / SD / Hybrid) Composition (FD stereo) Arrival direction (SD) LSS correlations / AGN correlations / auto-correlations III. Conclusions 2011/08/1 H. 7th TeVPA in Stockholm 2

3 The Telescope Array Collaboration ~120 researchers from Japan/US/Korea/Russia 2011/08/1 H. 7th TeVPA in Stockholm 3

4 TA detector Surface detector (SD) Plastic scintillator (a la AGASA) 507 SDs 1.2km spacing, 680km 2 Fluorescence detector (FD) 3 stations(br, LR, MD) 38 telescopes( ) (a la HiRes) Location Utah, USA ~200km south to Salt Lake City (39.3 o N, o W) ~1400m a.s.l. The largest detector in northern hemisphere 2011/08/1 H. 7th TeVPA in Stockholm 4

5 Surface Detector Radio communication Powered by solar cells 1.2 km spacing Plastic scintillator 3m 2, 1.2cm thickness 2 layers overlaid 50 MHz 12-bit FADC The SD array is in operation since March /08/1 H. 7th TeVPA in Stockholm 5

6 Fluorescence Detector (FD) BR/LR site:new FDs (3 o -18 o )x18 o camera (17.7 o -33 o )x18 o FOV: 3-33 o in elevation 108 o in azimuth 12 cameras/station Mirror φ 3.3m FADC readout (40 MHz sampling) ~1m Camera 16x16=256 PMTs Hamamatsu R /08/1 H. 7th TeVPA in Stockholm 6

7 FD station at MD site Transferred from HiRes 14 cameras/station 256 PMTs/camera 3 o -31 o elevation with 1 o pixel 114 o in azimuth 5.2m 2 mirror S/H electronics 2011/08/1 H. 7th TeVPA in Stockholm 7

8 Atmospheric monitor calibration (for fluorescence detectors) ELS 100 m Central Laser Facility Observe sidescattering of laser from each FD station as a standard candle LIDAR: Observe backscattering of laser measure transparency of atmosphere IR camera:cloud monitor Electron Light Source (ELS) End-to-end absolute energy calibration of fluorescence detectors BR site 2011/08/1 H. 7th TeVPA in Stockholm 8

9 ELS (Electron Light Source) [compact electron linear accelerator] Specification. electron energy: 40 MeV (max). current: 10 9 electrons/pulse. pulse width: 1 µsec By an electron beam with known total energy, we will perform end-to-end absolute energy calibration of FD. ELS First light View from the roof of FD station Image of pseudo shower by FD 2011/08/1 H. 7th TeVPA in Stockholm 9

10 Spectrum MD FD mono spectrum HiRes refurbished telescope Direct link of energy scales and energy spectra between HiRes and TA SD spectrum Plastic scintillator surface detectors (a la AGASA) Hybrid spectrum BRM/LR FD (new telescopes) + SD 2011/08/1 H. 7th TeVPA in Stockholm 10

11 Middle Drum (MD) FD Analysis 14 refurbish HiRes-1 telescopes TAMD mono processing is identical to HiRes-1 monocular one. Same program set, event selection, cuts Using the same average atmospheric model The differences the telescope location and pointing directions Thresholds (~20% lower than HiRes-1) 2011/08/1 H. 7th TeVPA in Stockholm 11

12 Impact parameter R p Black: TA MD data Red: MC 2011/08/1 H. 7th TeVPA in Stockholm 12

13 Zenith angle θ Black: TA MD data Red: MC 2011/08/1 H. 7th TeVPA in Stockholm 13

14 MD mono energy spectrum Data: 2007/Dec~2010/Dec Preliminary in good agreement with HiRes 2011/08/1 H. 7th TeVPA in Stockholm 14

15 SD spectrum SD reconstruction MC LDF, timing fit First energy estimation Data/MC comparisons SD energy vs. FD energy SD spectrum 2011/08/1 H. 7th TeVPA in Stockholm 15

16 SD data set May/11/2008 Apr/25/2011 (~3 years) Exposure ~2700km 2 sr yr Cuts: LDF χ 2 /ndf < 4.0 Border Cut > 1.2km Zenith Angle < 45 degrees Pointing direction uncertainty < 5 degrees Fractional S800 uncertainty < /08/1 H. 7th TeVPA in Stockholm 16

17 SD event reconstruction 2008/Jun/25-19:45: UTC Time fit to determine geometry ( modified Linsley) S800 Lateral Density Distribution Fit to determine S800 (charge density 800m from the shower axis) Fit with AGASA LDF r = 800m S(800) Primary Energy 2011/08/1 H. 7th TeVPA in Stockholm 17

18 SD Monte Carlo Simulate the data exactly as it exists. Start with previously measured spectrum and composition. Use Corsika/QGSJet-II air shower events thinned and de-thinned B.T.Stokes et al., arxiv: , arxiv: [astro-ph] Throw with isotropic distribution. Simulate detector response (GEANT4), trigger, front-end electronics, DAQ. Write out the MC events in same format as data. Analyze the MC with the same programs used for data. Test with data/mc comparison plots. 2011/08/1 H. 7th TeVPA in Stockholm 18

19 Time fit residual over sigma DATA MC Counter signal, [VEM/m 2 ] Fitting results Fitting procedures are derived solely from the data Same analysis is applied to MC Fit results are compared between data and MC MC fits the same way as the data. Consistency for both time fits and LDF fits. Corsika/QGSJet-II and data have same lateral distributions! 2011/08/1 H. 7th TeVPA in Stockholm 19

20 First Estimate of Energy θ(deg) Energy table is constructed from the MC First estimation of the event energy is done by interpolating between S800 vs sec(θ) lines 2011/08/1 H. 7th TeVPA in Stockholm 20

21 Energy Scale Energy scale is determined more accurately by FD than by CORSIKA QGSJET-II Set SD energy scale to FD energy scale using wellreconstructed events seen by both detectors. 27% renormalization E SD =E SD /1.27 Ratio of FD to SD after SD renormalization FD data from all three stations included. 2011/08/1 H. 7th TeVPA in Stockholm 21

22 Data/MC comparison Zenith angle (deg) azimuthal angle (deg) XCORE (m) Black: TA SD data Red: MC YCORE (m) 2011/08/1 H. 7th TeVPA in Stockholm 22

23 DATA/MC: S800, Energy S800 Black: TA SD data Red: MC Energy 2011/08/1 H. 7th TeVPA in Stockholm 23

24 Aperture and Exposure E > ev Aperture = 900 km 2 sr Exposure = 2700 km 2 sr yr Data set 2008/05/ /04/ days ~ 3 years GZK effect folded into the MC 2011/08/1 H. 7th TeVPA in Stockholm 24

25 TA SD and HiRes Spectra TA SD energy is rescaled to FD energy. in agreement with HiRes spectra 2011/08/1 H. 7th TeVPA in Stockholm 25

26 TA SD Spectrum Preliminary TA SD energy is rescaled to FD energy. 2011/08/1 H. 7th TeVPA in Stockholm 26

27 Significance of the Suppression TA SD energy is rescaled to FD energy. 2011/08/1 H. 7th TeVPA in Stockholm 27

28 Hybrid Spectrum Hybrid analysis FD mono analysis + SD information improve reconstruction Aperture is flat for >10 19 ev by SD The example of the Hybrid event 2008/12/30 LR FD station 2011/08/1 H. 7th TeVPA in Stockholm 28

29 Hybrid analysis: Data and MC Geometry: Hybrid Energy: FD Data: date: May/27/2008 Sep/7/2010 (~2.25years) BR + LR (new telescopes) with SDs Cut condition Xmax has to be observed. Zenith angle < 55degrees MC: Air shower: CORSIKA, QGSJET-II Isotropic distribution Detector : All of calibration constant with time dependence Simulate trigger, front-end electronics, and DAQ Aperture / Exposure 2011/08/1 H. 7th TeVPA in Stockholm 29

30 Geometrical reconstruction FD mono analysis + timing of one SD t i Mono reconstruction = t core 1 + c sinψ sinαi r sin( ψ + α ) i core Tube time (µs) Hybrid reconstruction 1 sinψ sinαi ti = tcore + r c sin( ψ + αi ) 1 tcore = tsd + ( rcore rsd )cosψ c Shower axis core α angle (deg) ψ t core r core 2011/08/1 H. 7th TeVPA in Stockholm 30 t SD αi r SD FD

31 Exposure The aperture is calculated from MC simulation. Exposure: ~6*10 15 m 2 sr 19 ev 2011/08/1 H. 7th TeVPA in Stockholm 31

32 Data/MC comparison impact parameter R p BR station LR station Red: TA data Blue: MC 2011/08/1 H. 7th TeVPA in Stockholm 32

33 Data/MC comparison zenith angle θ BR station LR station Red: TA data Blue: MC 2011/08/1 H. 7th TeVPA in Stockholm 33

34 Energy spectrum Hybrid events at the BR and LR station for TA 2.25 years item Fluorescence yield Systematic errors in energy measurement Systematic error 11% Atmosphere 11% Calibration 11% Reconstruction <12% Total 23% TA hybrid spectrum is in agreement with MD mono and SD spectra. 2011/08/1 H. 7th TeVPA in Stockholm 34

35 TA, AGASA, Auger, HiRes, AGASA spectra TA SD energy is scaled to FD energy. TA SD spectrum is consistent with TA MD mono and hybrid spectra, and consistent with HiRes-I and HiRes-II spectra. 2011/08/1 H. 7th TeVPA in Stockholm 35

36 FD stereo composition Measure Xmax for BR/LR FD stereo events Create simulated event set Apply the procedure exactly same as with the data LR FD station BR FD station Example of stereo event 2008/09/04 10:51: /08/1 H. 7th TeVPA in Stockholm 36

37 Data/MC comparison of Xmax ev ev ev ev ev ev Data points TA data Red histogram QGSJET-II proton Blue histogram QGSJET-II Fe ev ev Reconstructed Xmax (g/cm 2 ) preliminary 2011/08/1 H. 7th TeVPA in Stockholm 37

38 <Xmax> vs. loge <reconstruced Xmax> (g/cm 2 ) 1 log 10 (E/eV) 2011/08/1 H. 7th TeVPA in Stockholm 38

39 Arrival direction of UHECRs LSS correlation AGN correlation autocorrelation 2011/08/1 H. 7th TeVPA in Stockholm 39

40 Correlations with LSS LSS model:. Galaxies (2MASS XSCz catalog, from 5 Mpc to 250 Mpc ). The flux beyond 250 Mpc: uniform. Proton primaries assumed. All interactions and redshift losses are accounted for TA SD data (May 2008 to May 2011): light blue points (zenith angle < 45 o ) E CR >10 EeV, N CR =854 E CR >40 EeV, N CR =49 E CR >57 EeV, N CR = o 360 o 0 o -90 o Darker gray region indicates larger flux. Each region among five regions contains 1/5 of the total flux. Galactic coordinates 40

41 Correlations with LSS E CR > 10 EeV E CR > 40 EeV E CR > 57 EeV Probability preliminary 5% Data are compatible with LSS model at E CR > 40 EeV and 57 EeV With correction for GMF of strong halo component, data are compatible with LSS model at E CR >10 EeV. the disk component only does not improve. Data are compatible with isotropy. 41

42 Correlations with LSS Inclusion of Galactic Magnetic Field (GMF) Two-component structure: Antisymmetric halo + symmetric disk field Fits NVSS Rotation Measure (RM) data [Pshirkov et al., to appear in ApJ] 2011/08/1 H. 7th TeVPA in Stockholm 42

43 Correlations with AGN TA SD data beyond 57 EeV Veron catalog 12 th edition AGN z<0.018 Correlations of data with AGN within 3.1 o Number of TA data correlated with AGN Auger 2007 Number of TA data 43

44 Autocorrelation The number normalized by solid angle Separation angle θ of two UHECRs above 40 EeV 0 pair observed(1.1 expected bkg) for θ < 2.5 o Cumulative autocorrealtion Probability that the number of two-cr correlations is less than expectation E CR > 40 EeV E CR > 57 EeV The result is consistent with isotropy. 2011/08/1 H. 7th TeVPA in Stockholm 44

45 Summary The Telescope Array (TA) is the largest UHECR detector in the northern hemisphere. Hybrid and stereo observation by SD (a la AGASA: plastic scintillator) and FD (a la HiRes: new FDs and refurbished HiRes-I to TA) The SD array and FDs are operating with excellent reliability. End-to-end absolute energy calibration FD with ELS in the near future. The SD, FD mono, stereo, and hybrid analyses are being performed. The results of spectrum, composition, and arrival directions from TA are presented. More will come at the ICRC in Beijing. 2011/08/1 H. 7th TeVPA in Stockholm 45